[jpirko-mlxsw:petrm_resilient 5/5] net/ipv4/nexthop.c:2617:6: warning: variable 'err' is used uninitialized whenever 'if' condition is true

[jpirko-mlxsw:petrm_resilient 5/5] net/ipv4/nexthop.c:2617:6: warning: variable 'err' is used uninitialized whenever 'if' condition is true

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 3505 bytes --]

tree:   https://github.com/jpirko/linux_mlxsw petrm_resilient
head:   eb6c13f4558923f62bfb794b90fdbd041b103c75
commit: eb6c13f4558923f62bfb794b90fdbd041b103c75 [5/5] debugfs for nexthop [xxx]
config: mips-randconfig-r032-20201120 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 3ded927cf80ac519f9f9c4664fef08787f7c537d)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install mips cross compiling tool for clang build
        # apt-get install binutils-mips-linux-gnu
        # https://github.com/jpirko/linux_mlxsw/commit/eb6c13f4558923f62bfb794b90fdbd041b103c75
        git remote add jpirko-mlxsw https://github.com/jpirko/linux_mlxsw
        git fetch --no-tags jpirko-mlxsw petrm_resilient
        git checkout eb6c13f4558923f62bfb794b90fdbd041b103c75
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> net/ipv4/nexthop.c:2617:6: warning: variable 'err' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (pos == size)
               ^~~~~~~~~~~
   net/ipv4/nexthop.c:2650:9: note: uninitialized use occurs here
           return err ?: size;
                  ^~~
   net/ipv4/nexthop.c:2617:2: note: remove the 'if' if its condition is always false
           if (pos == size)
           ^~~~~~~~~~~~~~~~
   net/ipv4/nexthop.c:2613:9: note: initialize the variable 'err' to silence this warning
           int err;
                  ^
                   = 0
   1 warning generated.

vim +2617 net/ipv4/nexthop.c

  2600	
  2601	static ssize_t nexthop_dfs_bucket_activity_write(struct file *file,
  2602							 const char __user *user_buf,
  2603							 size_t size, loff_t *ppos)
  2604	{
  2605		const char *tok_bucketid;
  2606		const char *tok_nhid;
  2607		struct nexthop *nh;
  2608		loff_t pos = *ppos;
  2609		char buf[128];
  2610		u16 bucketid; // xxx or u32 if we choose so
  2611		char *ptr;
  2612		u32 nhid;
  2613		int err;
  2614	
  2615		if (pos < 0)
  2616			return -EINVAL;
> 2617		if (pos == size)
  2618			goto skip;
  2619		if (pos)
  2620			return -EINVAL;
  2621		if (size > sizeof(buf))
  2622			return -ENOMEM;
  2623	        if (copy_from_user(buf, user_buf, size))
  2624	                return -EFAULT;
  2625	
  2626		buf[sizeof(buf) - 1] = '\0';
  2627		ptr = buf;
  2628		tok_nhid = strsep(&ptr, " \t");
  2629		tok_bucketid = strsep(&ptr, " \t");
  2630	
  2631		if (!tok_nhid || !tok_bucketid || ptr)
  2632			return -EINVAL;
  2633	
  2634		err = kstrtou32(tok_nhid, 0, &nhid);
  2635		if (err)
  2636			return err;
  2637	
  2638		err = kstrtou16(tok_bucketid, 0, &bucketid);
  2639		if (err)
  2640			return err;
  2641	
  2642		rcu_read_lock();
  2643		nh = nexthop_find_by_id(&init_net, nhid);
  2644		if (!nh || !nexthop_select_path(nh, bucketid))
  2645			err = -ENOENT;
  2646		rcu_read_unlock();
  2647	
  2648	skip:
  2649		*ppos = size;
  2650		return err ?: size;
  2651	}
  2652	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

[-- Attachment #2: config.gz --]
[-- Type: application/gzip, Size: 26893 bytes --]